A congressional staffer has been charged with falsifying a security clearance form, the U.S. Attorney’s Office for the District of Columbia announced Wednesday evening.

Isaac Lanier Avant faces up to five years in prison for not disclosing on a security clearance form that he had failed to pay income taxes. Avant served as chief of staff for Rep. Bennie Thompson, D-Miss., and worked as deputy staff director and staff director the House Committee on Homeland Security.

Thompson is the top Democrat on the panel and Avant had to fill out a security clearance form for his work on the committee, known as the Standard Form 86, “Questionnaire for National Security Positions.”

The indictment alleges that Avant did not disclose that he had previously failed to file income taxes. In January, Avant was sentenced to four months of prison time for failing to file income tax returns, and must pay nearly $150,000 to the IRS. Avant’s prison sentence was to be served every weekend over a period of 12 months.

It is not clear if Avant is still employed by Thompson’s office. Data compiled by LegiStorm showed Avant receiving nearly $44,000 in 2017, with a gap between February and April. The last date for the payments is June 30.

A spokesman for Thompson’s office did not immediately respond to a request for comment.